SH7055S Datasheet, PDF (650/1002 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH RISC engine Family/SH7000 Series

17.4.4 External Triggering of A/D Conversion
A/D conversion can be externally triggered. To activate the A/D converter with an external
trigger, first set the pin functions with the PFC (pin function controller) and input a high level to
the ADTRG pin, then set the TRGE bit to 1 and clear the ADST bit to 0 in the A/D control register
(ADCR), and set the EXTRG bit to 1 in the A/D trigger register (ADTRGR). When a low level is
input to the ADTRG pin after these settings have been made, the A/D converter detects the low
level and sets the ADST bit to 1. If a low level is being input to the ADTRG pin when A/D
conversion ends, the ADST bit is set to 1 again, and A/D conversion is started. Figure 17.7 shows
the timing for external trigger input.
The ADST bit is set to 1 two states after the A/D converter samples the low level on the ADTRG
pin. The timing from setting of the ADST bit until the start of A/D conversion is the same as when
1 is written into the ADST bit by software.
pin sampled
Pφ
input
ADST bit
ADST = 1
Figure 17.7 External Trigger Input Timing
Rev.2.0, 07/03, page 612 of 960